Networking is used in many modern communication systems. Wired networking connections are made with copper or fiber optic cables connected to one or more network switches. FIG. 1 is a simplified diagram illustrating a network 10 including a network switch 12 and a plurality of remote nodes 14a, 14b, . . . , 14e, 14N of a set 14 of nodes. The nodes of set 14 are physically connected with network switch 12 by means of a set 16 of cables. The nodes of set 14 may be any type of computerized devices, such as computers, sensors, or the like. Each computerized device of set 14 of nodes is fitted with a “network interface card” of a set 18 of node network interface cards (NICs). More particularly, the computerized device of node 14a is fitted with a network interface card 18a, which includes a port 19a that interfaces with the associated end of network cable 16a. Similarly, the computerized device of node 14b is fitted with a network interface card 18b, which includes a port 19b that interfaces with the associated end of network cable 16b, . . . , the computerized device of node 14e is fitted with a network interface card 18e, which includes a port 19e that interfaces with the associated end of network cable 16e, and the computerized device of node 14N is fitted with a network interface card 18N, which includes a port 19N that interfaces with the associated end of network cable 16N. The network interface cards of set 18 of network interface cards provide for control of the interface between the computerized device or portion of each node of set 14 of nodes and the associated cable of set 16 of cables. While the network interfaces are styled “cards,” those skilled in the art know that the cards may not be manifested as separate printed-circuit boards, but rather each may be an integral portion of the motherboard of the associated computerized device. The computerized portion of network switch 12 similarly includes an appropriate interface to the network cables of set 16 of cables. Since the computerized portion of network switch 12 interfaces with a plurality of cables, it requires a plurality of “network interface cards,” illustrated as a set 20 of network interface cards (NICs). As with the case of the network interface cards of the network nodes, the network interface cards associated with network switch 12 may not be separate cards, but may be integrated onto the motherboard of the network switch 12. Each network interface card of set 20 defines a port of set 21 of ports by which the network switch 12 communicates with remote network nodes of set 14. In FIG. 1, set 20 of interface cards includes an interface card 20a, which includes a port 21a that interfaces the computerized portion of network switch 12 with network cable 16a at a port 21a, an interface card 20b, which includes a port 21b that interfaces the computerized portion of network switch 12 at port 21b with network cable 16b, . . . , an interface card 20e, which interfaces the computerized portion of network switch 12 at a port 21e with network cable 16e, and an interface card 20N, which interfaces the computerized portion of network switch 12 at a port 21N with network cable 16N.
FIG. 2 is a simplified diagram illustrating a portion 200 of a network such as network 10 of FIG. 1. In FIG. 2, elements corresponding to those of FIG. 1 are designated by like reference alphanumerics. In FIG. 2, a computerized node portion 14n communicates data with a data transceiver (TX/RX) 220n of a network switch 12. Computerized node portion 14, communicates by way of a path including a port 219n, a path 218n, and port 19, of network interface cards (NIC) 18n, cable path 16n, and port 21n, path 221n, and port 223, of NIC 20, of set 20 of network interface cards. That is, data or information flows in both directions over cable 16n between computerized node portion 14n and port 226, of network switch 12 and its data transceiver 220n. Similarly, a computerized node portion 14n+1 communicates data with a data transceiver (TX/Rx) 220n+1 by way of a path including a port 219n+1, a path 218n+1, and a port 19n+1 of network interface card (NIC) 18n+1, and by cable path 16n+1 to port 21n+1, path 221n+1, and port 223n+1 of network interface card 20n+1 of network switch 12, and to port 226n+1 of data transceiver (Tx/Rx) 220n+1. That is, data or information flows in both directions over cable 16n+1 between computerized portion 14n+1 and data transceiver 220n+1. Each data transceiver 220n, 220n+1 responds to the flow of data over its associated port by producing an indicator enable signal. The indicator is often a light-emitting device such as a light-emitting diode or laser, designated 222n and 222n+1 in FIG. 2. In operation of the arrangement of FIG. 2, data flowing through path 16, causes transceiver 220n to generate a drive signal which is applied by a path 225n to indicator lamp 222n, and data flowing through path 16n+1 causes transceiver 220n+1 to generate a drive signal which is applied by way of a path 225n+1 to an indicator lamp 222n+1. The indicator lamps are usually arranged in a side-by-side line array, which makes it possible to compare channel indications and to identify those having out-of-the-ordinary indications. Thus, examination of the indicator lamp of each channel or path can give an indication of the flow of data, or lack thereof, between the node of set 14 (and its NIC) associated with the channel and the corresponding port (and is NIC) of the network switch 12. Very often a variable or changing voltage is applied to the indicator lamps, giving the appearance of “flickering.” This is commonly accomplished by applying a sample of the data to the associated indicator lamp.
While the data transceivers 220n, . . . , 220n+1 of FIG. 2 are illustrated as being located within the network switch 12, they may if desired be located within the associated network interface card. Thus, for example, data transceiver 220, may be located within network interface card 20n. If the transceiver 220n is located in network interface card 20n, the data flowing to and from the transceiver would be communicated by a path 290n with switch 12, and likewise transceiver 220n+1 would communicate by a path 290n+1 with network switch 12. Those skilled in the art will understand that this partitioning is conceptually simple.
While there may be a physical cable connection between any particular remote node of set 14 of remote nodes (and its NIC) and a port of network switch 12, data communication is only possible if switch 12 “recognizes” node 14 to be on the same virtual local area network (VLAN) as the switch 12. This may be termed a “logical” connection. Thus, the presence of illumination of the indicator lamp of a particular channel is a sure indication of a logical connection or activity on the associated cable, and is therefore also a sure indication that the cable is physically connected at one end to a node and at the other end to an associated port of the network switch 12, else communication would not be possible.
As mentioned, many node devices can be connected to network switches. During the initial setup of a network, some network nodes connections to a network switch may be left inactive or configured for a different VLAN on the switch. That is, the nodes may be physically connected to ports of the network switch, but not logically connected. As a result, some nodes may not be logically connected to the network, even though physically connected to the switch by a cable. When not logically connected, cables coming out of a node cannot be traced “back” to the corresponding port of the network switch(es) using standard operating system commands like “ping” or “traceroute”. This means that when these physically-connected but logically-disconnected nodes are to be used, their cable connection must be made or verified. In short, the cable must be traced from the node network card port to the desired switch port. The tracing problem is exacerbated by the large number of cables or network connections, as there may be as many as 300 cables connected to each network switch. There are different tracing methods. One approach is for a network technician to do trial and error. This task is made simpler if the cables are labeled, but even when the cables are coded, looking up a label code on every cable can take a long time. This method is both inefficient and time-consuming.
Simple arrangements are desired which allow physical connection tracing.